There is an incandescent lamp including a bulb which is formed of soft glass and in which a sealing section is provided in an end portion thereof, a pair of lead sections of which one end side extends inside the bulb and the other end side is exposed from the sealing section, a filament section which is provided between end portions of the pair of lead sections inside the bulb, and a fixing member (also referred to as a bridge glass and the like) that is formed of the soft glass holding the pair of lead sections inside the bulb.
Here, the sealing section is formed by heating the end portion of the bulb formed of the soft glass and crushing the end portion of the heated bulb together with the pair of lead sections.
Furthermore, the fixing member is formed by crushing a member formed of the heated soft glass together with the pair of lead sections.
Thus, the pair of lead sections is formed of Dumet wire having a thermal expansion coefficient close to a thermal expansion coefficient of a glass.
However, if the pair of lead sections are formed of the Dumet wire, there is a problem that a portion holding the filament section of the pair of lead sections is open and failure occurs due to non-conduction while repeatedly turning on and off.
Thus, the pair of lead sections was proposed, in which the filament section side is formed of nickel and the sealing section side is formed of the Dumet wire.
However, a positional relationship was not considered between a portion formed of nickel in the pair of lead sections, a joint portion with a portion formed of the Dumet wire, and the fixing member formed of the soft glass.
Thus, when manufacturing an incandescent lamp, there is a concern that the fixing member is chipped and glass pieces are generated inside the bulb.
If there are the glass pieces inside the bulb, there is a concern that the glass pieces are attached to the filament section and then disconnection occurs.
Furthermore, since a portion of the lead sections having the filament section is heated by lighting on, there is a concern that an alloy is formed by nickel of the lead sections and tungsten of the filament section. If the alloy of nickel and tungsten is formed, the end portion of the filament section becomes brittle and disconnection may occur.
Furthermore, a technique was also proposed in which the pair of lead sections are formed of molybdenum.
However, if the pair of lead sections are simply formed of molybdenum, it is difficult to perform plastic working (bending working) when holding the filament section on the lead sections.